The present invention relates to a thin push switch used in a portable electronic device such as a mobile telephone or a portable headphone stereo player.
As portable electronic apparatuses have been having a reduced size or thickness, downsizing of push switches in the device is significantly desired. A conventional push switch having a reduced size or thickness for optimum downsizing is disclosed in Japanese Patent Laid-open No.7-254327, and will be explained below referring to the relevant drawings.
FIGS. 8 and 9 are a perspective view and an exploded perspective view of the conventional push switch, respectively. A bottom metal plate 1 of the push switch has a fixed contact 2 provided on the center thereof, and also has first external terminals 1A formed on one edge thereof which are downwardly bent in an L-shape. The metal plate 1 has notches 1B formed at the opposite edge thereof having a specific width. An adhesive insulating sheet 3 having both surfaces thereof coated with an adhesive agent is bonded at the lower side with the adhesive agent to the upper side of the bottom metal plate l. The adhesive insulating sheet 3 has a center opening 3A formed therein. Upon being bonded to the bottom metal plate 1, the bottom metal plate 1 has a center contact 2 positioned a center of the center opening 3A, and has an upper end of the center contact exposed upward through the center opening 3A. The adhesive insulating sheet 3 includes notches 3B formed corresponding to the notches 1B formed at the other edge of the bottom metal plate 1. The adhesive insulating sheet 3 is bonded with an elastic metal plate 4 at the upper side thereof with the adhesive agent. The elastic metal plate 4 includes a dome-shaped projection 5 swelling upward at the center of the plate 4. The lower side of the projection 5 is positioned opposite to and spaced from the fixed contact 2 at the center of the plate 1. The elastic metal plate 4 has second external terminals 4A formed with bent downward in an L-shape. The second external terminals 4A extend downward through the notches 3B of the adhesive insulating sheet 3 and the notches 1B of the bottom metal plate 1 with being electrically isolated from the bottom metal plate 1.
An operation of the conventional push switch will be explained. Upon being depressed downward with a pressure, the dome-shaped projection 5 of the elastic metal plate 4 has the dome shape inverted with a click feel, and has the lower side directly contacts with the fixed contact 2 of the bottom metal plate 1. This allows the elastic metal plate 4 and the bottom metal plate 1 to electrically conducts to each other, thus turning on the switch, i.e. the first external terminals 1A and the second external terminals 4A conducts to each other. Upon being released from the pressure, the dome-shaped projection 5 can return back to the original shape by an own elasticity, thus electrically disconnecting between the bottom metal plate 1 and the elastic metal plate 4 and turning off the switch.
The conventional push switch includes the bottom metal plate 1 and the elastic metal plate 4 bonded to each other with the adhesive agent of the adhesive insulating sheet 3. It is however difficult to control and maintain the thickness and adhesivity of the adhesive agent coated on both sides of the adhesive insulating sheet 3, and hence, extra steps for adjustment in the production of the switch is required.
A thin push switch includes a less number of components joined together without adhesive, causing a trouble, in the handling, and can thus be favored with mass production.
The push switch includes the following elements:
(A) A fixed plate including a fixed contact at the center thereof, first cramp-locking sections respectively provided at a pair of first ends opposite to each other, and a first terminal electrically connected with the fixed plate;
(B) A contact plate, which faces the fixed plate, including a movable contact facing the fixed contact, second cramp-locking sections respectively provided at a pair of second ends opposite to each other which are disposed at different positions from the first opposite ends of the fixed plate, and second terminals electrically connected with the movable contact; and
(C) An insulating spacer, which is disposed between the fixed plate and the contact plate, including first cramp-locked tabs being positioned corresponding to the first ends and cramp-locked by the first cramp-locking sections, second cramp-locked tabs being positioned corresponding to the second ends and cramp-locked by the second cramp-locking sections, and an opening facing the fixed contact.